alert http $HOME_NET any -> $EXTERNAL_NET any (msg:"ET MALWARE Cobalt Strike Related Activity (GET)"; flow:established,to_server; http.method; content:"GET"; http.uri; content:"/chunky/"; fast_pattern; pcre:"/^[A-Za-z0-9-_]{176}\//R"; content:".gif"; endswith; http.header_names; content:!"Referer"; reference:md5,1cb5a9c2bc4adfe101f6069d525ba9b2; reference:url,twitter.com/malware_traffic/status/1600933614531010561; classtype:trojan-activity; sid:2042538; rev:1; metadata:attack_target Client_Endpoint, created_at 2022_12_09, deployment Perimeter, deployment SSLDecrypt, malware_family Cobalt_Strike, confidence High, signature_severity Major, tag Description_Generated_By_Proofpoint_Nexus, updated_at 2022_12_09; target:src_ip;)